Analog isolation system with digital communication across a capacitive barrier

• US 6,683,548 B2
• Filed: 01/17/2003
• Issued: 01/27/2004
• Est. Priority Date: 04/22/1997
• Status: Expired due to Fees

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Welland, David R., Scott, Jeffrey W., Sooch, Navdeep S.
• Primary Examiner(s): YOUNG, BRIAN K
• Application Number:
  US10/346,584
• Publication Number:
  US 20030107505A1
• Time in Patent Office: 375 Days
• Field of Search: 341/110, 341/143, 341/144, 341/155, 379/412, 113/99
• US Class Current: 341/110
• CPC Class Codes: H04B 14/062 using delta modulation or one-bit differential modulation [1DPCM]
• CPC Class Codes: H04L 25/0266 Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: H04L 25/06 Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier. Finally, a bidirectional isolation system is provided whereby bidirectional communication of digital signals is accomplished using a single pair of isolation capacitors. In preferred embodiments, the digital data communicated across the barrier consists of digital delta-sigma data signals multiplexed in time with other digital control, signaling and framing information.

Claims

1. Phone line direct access arrangement circuitry configured to isolate a system side integrated circuit device from a phone line through a plurality of isolation elements, comprising:

a system side integrated circuit device configured to communicate a first digital differential signal to at least two of the plurality of isolation elements, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, wherein the system side integrated circuit device is further configured to be isolated from the phone line in order to satisfy phone line isolation regulatory standards;

a line side integrated circuit device configured to communicate a second digital differential signal to the first isolation capacitor and the second isolation capacitor so that the first and second digital differential signals are communicated across the same first and second isolation capacitors and so that the first and second isolation capacitors bidirectionally transfer the first and second digital differential signals, the line side integrated circuit device further configured to provide an output signal for sending data to a phone line;

wherein the system side integrated circuit device is further configured to provide a clock signal to the line side integrated circuit device through at least one of the plurality of isolation elements; and

wherein the system side integrated circuit device and the line side integrated circuit device are configured so that power is capable of being provided from the system side integrated circuit device to the line side integrated circuit device while still maintaining the isolation required by the phone line isolation regulatory standards.

2. The circuitry of claim 1, wherein the system side integrated circuit device is further configured to generate at least one power supply within the line side integrated circuit device from the power provided from the system side integrated circuit device.

3. The circuitry of claim 2, wherein the line side integrated circuit device includes a power supply circuit to generate the at least one power supply, the power supply circuit comprising at least a rectifier circuit and a filter circuit.

4. The circuitry of claim 3, wherein the rectifier circuit comprises an active diode bridge.

5. The circuitry of claim 3, wherein the filter circuit comprises at least one capacitor.

6. The circuitry of claim 1, wherein the system side integrated circuit device is further configured to provide the clock signal to the line side integrated circuit device through an isolation element that is separate from the first isolation capacitor and the second isolation capacitor.

7. The circuitry of claim 1, wherein the system side integrated circuit device is further configured to provide the clock signal to the line side integrated circuit device through the first isolation capacitor and the second isolation capacitor.

8. The circuitry of claim 1, wherein the system side integrated circuit device includes a system side ground and the isolated side integrated circuit device includes an isolated side ground.

9. The circuitry of claim 1, wherein the first digital differential signal includes both data information and control information.

10. The circuitry of claim 1, wherein the second digital differential signal includes both data information and control information.

11. The circuitry of claim 9, wherein the control information includes framing information.

12. The circuitry of claim 9, wherein the first digital differential signal includes both data information and control information.

13. The circuitry of claim 1, wherein each of said plurality of isolation elements comprises a capacitor.

14. The circuitry of claim 1, wherein a portion of said plurality of isolation elements each comprises a capacitor.

15. Phone line direct access arrangement circuitry for a phone line, comprising:

a system side integrated circuit device configured to communicate a first digital differential signal to at least a first isolation capacitor and a second isolation capacitor, wherein the system side integrated circuit device is further configured so that it may be isolated from the phone line in order to satisfy phone line isolation regulatory standards;

a line side integrated circuit device configured to communicate a second digital differential signal to the first isolation capacitor and the second isolation capacitor so that the first and second digital differential signals are communicated across the same first and second isolation capacitors and so that the first and second isolation capacitors bidirectionally transfer the first and second digital differential signals;

wherein the system side integrated circuit device is further configured to provide a clock signal to the line side integrated circuit device through at least one of a plurality of isolation elements, said at least one of a plurality of isolation elements being separate from the first isolation capacitor and the second isolation capacitor; and

wherein the system side integrated circuit device and the line side integrated circuit device are configured so that power is capable of being provided from the system side integrated circuit device to the line side integrated circuit device while still maintaining the isolation required by the phone line isolation regulatory standards.

16. The circuitry of claim 15, wherein the system side integrated circuit device is configured to generate at least one power supply within the line side integrated circuit device from the power provided from the system side integrated circuit device.

17. The circuitry of claim 15, wherein the line side integrated circuit device includes a power supply circuit to generate the at least one power supply, the power supply circuit comprising at least a rectifier circuit and a filter circuit.

18. The circuitry of claim 17, wherein the filter circuit comprises at least one capacitor.

19. The circuitry of claim 15, wherein the first digital differential signal includes both data information and control information.

20. The circuitry of claim 15, wherein the second digital differential signal includes both data information and control information.

21. The circuitry of claim 20, wherein the control information includes framing information.

22. The circuitry of claim 20, wherein the first digital differential signal includes both data information and control information.

23. The circuitry of claim 15, wherein each of said plurality of isolation elements comprises a capacitor.

24. The circuitry of claim 15, wherein a portion of said plurality of isolation elements each comprises a capacitor.

25. Phone line direct access arrangement circuitry configured to isolate a system side integrated circuit device from a phone line through a plurality of isolation elements, comprising:

a system side integrated circuit device configured to communicate a first digital differential signal to at least two of the plurality of isolation elements, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, wherein the system side integrated circuit device is further configured to be isolated from the phone line in order to satisfy phone line isolation regulatory standards;

a line side integrated circuit device configured to communicate a second digital differential signal to the first isolation capacitor and the second isolation capacitor so that the first and second digital differential signals are communicated across the same first and second isolation capacitors and so that the first and second isolation capacitors bidirectionally transfer the first and second digital differential signals, the line side integrated circuit device further configured to provide an output signal for sending data to a phone line;

wherein the system side integrated circuit device is further configured to provide a clock signal to the line side integrated circuit device through at least one of the plurality of isolation elements;

wherein the system side integrated circuit device and the line side integrated circuit device are configured so that power is capable of being provided from the system side integrated circuit device to the line side integrated circuit device while still maintaining the isolation required by the phone line isolation regulatory standards; and

wherein at least one of the first digital differential signal and the second digital differential signal includes both data and control information.

26. The circuitry of claim 25, wherein the system side integrated circuit device is further configured to generate at least one power supply within the line side integrated circuit device from the power provided from the system side integrated circuit device.

27. The circuitry of claim 26, wherein the line side integrated circuit device includes a power supply circuit to generate the at least one power supply, the power supply circuit comprising at least a rectifier circuit and a filter circuit.

28. The circuitry of claim 27, wherein the rectifier circuit comprises an active diode bridge.

29. The circuitry of claim 27, wherein the filter circuit comprises at least one capacitor.

30. The circuitry of claim 25, wherein the system side integrated circuit device is further configured to provide the clock signal to the line side integrated circuit device through an isolation element that is separate from the first isolation capacitor and the second isolation capacitor.

31. The circuitry of claim 25, wherein the system side integrated circuit device is further configured to provide the clock signal to the line side integrated circuit device through the first isolation capacitor and the second isolation capacitor.

32. The circuitry of claim 25, wherein both the first and second digital differential signals include both data information and control information.

33. The circuitry of claim 32, wherein the control information includes framing information.

34. The circuitry of claim 25, wherein each of said plurality of isolation elements comprises a capacitor.

35. The circuitry of claim 25, wherein a portion of said plurality of isolation elements each comprises a capacitor.

36. Phone line direct access arrangement circuitry configured to isolate a system side integrated circuit device from a phone line through a plurality of isolation elements, comprising:

a system side integrated circuit device configured to communicate a first digital differential signal to at least two of the plurality of isolation elements, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, wherein the system side integrated circuit device is further configured to be isolated from the phone line in order to satisfy phone line isolation regulatory standards;

a line side integrated circuit device configured to communicate a second digital differential signal to the first isolation capacitor and the second isolation capacitor so that the first and second digital differential signals are communicated across the same first and second isolation capacitors and so that the first and second isolation capacitors bidirectionally transfer the first and second digital differential signals, the line side integrated circuit device further configured to provide an output signal for sending data to a phone line;

wherein at least one of the first digital differential signal and the second digital differential signal includes both data and control information.

37. The circuitry of claim 36, wherein the system side integrated circuit device is further configured to provide a clock signal to the line side integrated circuit device through at least one of the plurality of isolation elements.

38. The circuitry of claim 37, wherein the system side integrated circuit device is further configured to provide a clock signal to the line side integrated circuit device through an isolation element that is separate from the first isolation capacitor and the second isolation capacitor.

39. The circuitry of claim 36, wherein the system side integrated circuit device and the line side integrated circuit device are further configured so that power is capable of being provided from the system side integrated circuit device to the line side integrated circuit device while still maintaining the isolation required by the phone line isolation regulatory standards.

40. The circuitry of claim 36, wherein the system side integrated circuit device is further configured to generate at least one power supply within the line side integrated circuit device from the power provided from the system side integrated circuit device.

41. The circuitry of claim 40, wherein the line side integrated circuit device includes a power supply circuit to generate the at least one power supply, the power supply circuit comprising at least a rectifier circuit and a filter circuit.

42. The circuitry of claim 36, wherein both the first and second digital differential signals include both data information and control information.

43. The circuitry of claim 42, wherein the control information includes framing information.

44. The circuitry of claim 36, wherein each of said plurality of isolation elements comprises a capacitor.

45. The circuitry of claim 36, wherein a portion of said plurality of isolation elements each comprises a capacitor.

46. Phone line direct access arrangement circuitry configured to isolate a system side integrated circuit device from a phone line through a plurality of isolation elements, comprising:

a system side integrated circuit device further configured to communicate a first digital differential signal to at least two of the plurality of isolation elements, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, wherein the system side integrated circuit device is further configured to be isolated from the phone line in order to satisfy phone line isolation regulatory standards;

a line side integrated circuit device configured to communicate a second digital differential signal to the first isolation capacitor and the second isolation capacitor so that the first and second digital differential signals are communicated across the same first and second isolation capacitors and so that the first and second isolation capacitors bidirectionally transfer the first and second digital differential signals, the line side integrated circuit device further configured to provide an output signal for sending data to a phone line;

wherein the system side integrated circuit device is further configured to provide a clock signal to the line side integrated circuit device through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor;

wherein the system side integrated circuit device and the line side integrated circuit device are configured so that power is capable of being provided from the system side integrated circuit device to the line side integrated circuit device to generate at least one power supply within the line side integrated circuit device, while still maintaining the isolation required by the phone line isolation regulatory standards; and

wherein at least one of the first digital differential signal and the second digital differential signal includes both data and control information.

47. The circuitry of claim 46, wherein the line side integrated circuit device includes a power supply circuit to generate the at least one power supply, the power supply circuit comprising at least a rectifier circuit and a filter circuit.

48. The circuitry of claim 46, wherein the system side integrated circuit device includes a system side ground and the isolated side integrated circuit device includes an isolated side ground.

49. The circuitry of claim 46, wherein the first digital differential signal includes both data information and control information.

50. The circuitry of claim 46, wherein the second digital differential signal includes both data information and control information.

51. The circuitry of claim 46, wherein the control information includes framing information.

52. The circuitry of claim 46, wherein both the first and second digital differential signals include both data information and control information.

53. The circuitry of claim 52, wherein the control information includes framing information.

54. The circuitry of claim 46, wherein each of said plurality of isolation elements comprises a capacitor.

55. The circuitry of claim 46, wherein a portion of said plurality of isolation element each comprises a capacitor.